TORONTO, Feb. 15, 2013 /CNW/ - The Institute for Catastrophic Loss
Reduction (ICLR) today released a study on urban flooding in Canada
which looks at, among other topics, interpretation of building and
plumbing code wordings that relate to installation of backwater valves
to protect homes from sewer backup. While a significant amount of
research by ICLR and others has concluded that resolution of building
code enforcement issues may result in reduced vulnerability to extreme natural hazards,
issues surrounding code interpretation have not previously been studied.

Urban flood damages are a recurrent and growing issue for
municipalities, insurers and homeowners across Canada. Damages from
urban flood events often total in the $10s- and $100s of millions of
dollars. In May, 2012, a storm system that affected Thunder Bay and
moved through to Montréal resulted in $260 million in insured damages.
In July, 2012, a storm moved through southern Ontario affecting several
neighbourhoods in Hamilton and Ottawa, resulting in $90 million in
insured damages. An extreme rainfall event that affected a large region
of southern Ontario from Hamilton to Durham Region in August, 2005
resulted in over $500 million in insured damages, $247 million of which
was associated with sewer backup. Also in 2005, heavy rainfall and
associated flooding resulted in $300 million in insured damages in
southern Alberta. A severe storm in Edmonton, Alberta in 2004 resulted
in approximately $166 million in insured damages, $143 million of which
were associated with sewer backup.

Previous research conducted by ICLR revealed that a mainline, full port,
normally open backwater valve, when properly installed and maintained,
in tandem with the severance of foundation drains (i.e. weeping tile)
from the sanitary sewer, is one of the best measures a homeowner can
take to reduce the risk of stormwater and/or sewage backing up into a
basement. But building code/plumbing code and/or local by-law
requirements to install such valves in new homes is spotty across the
country, largely owing to code interpretation.

The study revealed that backwater valve building/plumbing code wordings
are interpreted differently across the country, though there is greater
interpretation consistency in some regions than in others.
Specifically, the survey revealed that 19% of British Columbia
respondents, 81% of Alberta respondents, 86% of Saskatchewan
respondents, 72% of Manitoba respondents, 26% of Ontario respondents
and 58% of respondents from New Brunswick and Nova Scotia interpreted
code wordings in a manner that required backwater valves to be
installed in all or most new homes. The study further revealed that
interpreting code wordings in this manner was strongly correlated with
a higher frequency of installation of backwater valves in new homes,
indicating the importance of code interpretation for backwater valve
installation.

According to Dan Sandink, study author, "Despite the fact that the
National Building Code of Canada and virtually all provinces use near
identical code wordings in the backwater valve sections of their
respective building and/or plumbing codes, this study found that there
are differing interpretations of code wordings, resulting in differing
frequencies of installation of backwater valves. So, while building and
plumbing officials in many jurisdictions in Canada interpret the code
as meaning that all new homes should have backwater valves, some
officials in some jurisdictions interpret the code as meaning that
backwater valves shall be used only in certain circumstances."

The primary recommendation of this report is that sentences in the
National Plumbing Code and provincial building and/or plumbing codes
that relate to installation of backwater valves to protect against
sewer backflow be reworded or clarified to ensure they are clearly and
consistently interpreted and applied.

According to the study, there are many advantages of installing
backwater valves in new homes. Due to the unpredictable nature of
extreme rainfall events and the unpredictability of infiltration and
inflow (I/I) in relatively new, separated sewer systems, it is often
impossible to identify which regions of an urban municipality are
exposed to sewer backup risk until widespread or regional sewer backup
events have occurred. It is also more economical to install backwater
valves in new homes when compared to retrofitting valves into existing
homes. For example, several Canadian municipalities provide partial
retrofit subsidies of several thousand dollars for the retrofit of
backwater valves, while installation of valves in new homes costs
approximately $250. Requiring installation of valves in new homes would
also help offset relatively low uptake frequencies for municipal
subsidy programs aimed at encouraging homeowners to adopt urban flood
risk reduction measures.

Established in 1998 by Canada's property and casualty insurers, ICLR is
an independent, not-for-profit research institute based in Toronto and
at Western University in London, Canada. ICLR is a centre of excellence
for disaster loss prevention research and education. ICLR's research
staff is internationally recognized for pioneering work in a number of
fields including wind and seismic engineering, atmospheric sciences,
water resources engineering and economics. Multi-disciplined research
is a foundation for ICLR's work to build communities more resilient to
disasters.